How to write state machines with c#?

Question

I need to write state machines that run fast in c#. I like the Windows Workflow Foundation library, but it's too slow and over crowded with features (i.e. heavy). I need something faster, ideally with a graphical utility to design the diagrams, and then spit out c# code. Any suggestions? Thanks!

Answer 1

Ultimately, you probably want the newly redesigned WF engine in .NET 4.0, as it is much faster and provides a flowchart activity (not quite a state machine, but works for most scenarios) and a nice designer UI experience. But since it's not yet released, that is probably not a good answer for now.

As an alternative, you could try stateless, a library specifically for creating state machine programs in .NET. It doesn't appear to provide a UI, but looks well-suited to fulfill your other goals.

Answer 2

Yeah, Microsoft may have been ahead of their time with State Machine WF. Sequential Workflows are being received much better.

When we decided on using a state machine, we rolled our own. because we couldn't find an acceptable framework with a UI. Here are our steps. Hope they'll help you.

1. Create your state interface:

   public interface IApplicationState { void ClickOnAddFindings();
   void ClickOnViewReport(); //And so forth

   }

2. Create the states and have them implement the interface:

   public class AddFindingsState : IApplicationState { frmMain _mForm;

   public AddFindingsState(frmMain mForm)
   {
       this._mForm = mForm;
   }
   
   
   public void ClickOnAddFindings()
   {            
   }
   
   
   public void ClickOnViewReport()
   {
       // Set the State
       _mForm.SetState(_mForm.GetViewTheReportState());
   }
   

   }

3. Instantiate the states in your main class.

   IApplicationState _addFindingsState;
   IApplicationState _viewTheReportState;
   _addFindingsState = new AddFindingsState(this);
   _viewTheReportState = new ViewTheReportState(this);
   

4. When the user does something requiring a change of state, call the methods to set the state: _state.ClickOnAFinding();

Of course, the actions will live in the particular instance of the IApplicationState.